Ordinarily, ionic liquids (also called ambient-temperature molten salts) are nonvolatile and flame retardant liquids that have no flash point. For this reason, they are employed in various electrolytes of electrochemical devices or as constituent elements thereof, with the expectation of contributing to enhance device safety. Their use has been considered, for instance, in electrochemical devices (typically, secondary batteries) in which overcharge may occur due to erroneous operation or the like. Japanese Patent Application Laid-open Publication No. 2003-331918 describes a technology in which an ambient-temperature molten salt, which combines a specific cyclic ammonium cation and a specific anion, is used as a solvent of the electrolyte of a lithium secondary battery. Japanese Patent Application Laid-open Publication No. 2004-253357 is another prior art document that relates to an electrolyte using an ambient-temperature molten salt. Further, Japanese Patent Application Laid-open Publication No. H11-307123 is a prior art document that, although not related to an ambient-temperature molten salt, relates to an electrolyte composition that enhances the safety of a lithium secondary battery (by making the electrolyte non-combustible).